[RndTbl] transistor wall-clock

[Daryl F]

On October 17, 2015 6:09:21 PM CDT, Tim Lavoie <tim at fractaldragon.net> wrote:
>The AC frequency as a clock source will also be a problem of the
>utility happens to mess with that timing. Forget why the do, but it
>happens.
>
>> On Oct 17, 2015, at 14:36, Trevor Cordes <trevor at tecnopolis.ca>
>wrote:
>> 
>> Off-topic, but cool:
>> 
>>
>http://www.transistorclock.com/?imm_mid=0da80b&cmp=em-prog-na-na-newsltr_20151017
>> 
>> A guy selling kits to make a all-parts-exposed digital wall clock
>that 
>> uses *no ICs* and *no crystals*.  You build it yourself, 1250 parts
>to 
>> solder onto a custom board.  Too pricey for me, otherwise I'd love to
>put 
>> one together.
>> 
>> ICYW, I dug around the FAQ and he is cheating a bit: he's using the
>60Hz 
>> of the AC as a timer source.
>> 
>> Hmm, since it plus into AC, does that mean touching some parts of the
>
>> exposed circuits might give you a nice zap?
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When the A/C grid is heavily loaded the generators slow below 60Hz.

The make up for it in later by generating higher than 60Hz.  That's why the old A/C clocks with synchronous motors never need correction over long periods of time.

Most cheap digital clocks haven't had the oscillator regulated so their time creeps off.

NTP fan, Daryl
-- 
Daryl F
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